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Abstract:

A system and method for uniform light generation in projection display
systems. An illumination source comprises a light source to produce
colored light, and a scrolling optics unit optically coupled to the light
source, the scrolling optics unit configured to create lines of colored
light from the colored light, and to scroll the lines of colored light
along a direction orthogonal to a light path of the illumination source.
The scrolling optics unit comprises a single light shaping diffuser to
transform the colored light into the lines of colored light, an optical
filter positioned in the light path after the light shaping diffuser, and
a scrolling optics element positioned in the light path after the optical
filter. The single light shaping diffuser is capable of simultaneously
transforming colored light into lines of colored light having
substantially uniform intensity to provide uniform illumination.

Claims:

1. An illumination source comprising:a light source to produce colored
light; anda scrolling optics unit optically coupled to the light source,
the scrolling optics unit configured to create lines of colored light
from the colored light, and to scroll the lines of colored light along a
direction orthogonal to a light path of the illumination source, wherein
the scrolling optics unit comprises,a single light shaping diffuser to
transform the colored light into the lines of colored light,an optical
filter positioned in the light path after the light shaping diffuser, the
optical filter configured to shape the lines of colored light, anda
scrolling optics element positioned in the light path after the optical
filter, the scrolling optics element configured to move the lines of
colored light in the direction orthogonal to the light path.

2. The illumination source of claim 1, wherein the scrolling optics
element is selected from the group consisting of: a rotating reflective
polygon, a rotating refractive polygon, a flower wheel, and combinations
thereof.

3. The illumination source of claim 2 further comprising a motor coupled
to the scrolling optics element, the motor configured to rotate the
scrolling optics element.

4. The illumination source of claim 1, wherein the light source
comprises:a set of coherent light sources, each coherent light source
configured to produce colored light in a specified wavelength range; anda
set of light collimators, each light collimator optically coupled to a
coherent light source in the set of coherent light sources, the light
collimator to substantially parallelize coherent light produced by a
corresponding coherent light source.

6. The illumination source of claim 1, wherein the light shaping diffuser
is capable of substantially simultaneously transforming colored light
from the light source into lines of colored light.

7. The illumination source of claim 6, wherein the light shaping diffuser
comprises light diffusing structures oriented in a direction orthogonal
to an orientation of the lines of colored light.

8. The illumination source of claim 7, wherein the light shaping diffuser
comprises an array of lenticular elements, and wherein the array has a
pitch substantially greater than a longest light wavelength produced by
the light source.

9. The illumination source of claim 7, wherein the light shaping diffuser
comprises randomly or pseudorandomly arranged structures having
consistent orientation, and wherein each structure has a feature size
substantially greater than a longest light wavelength produced by the
light source.

10. The illumination source of claim 1, wherein the optical filter
comprises an optically opaque body having multiple slit apertures,
wherein the slit apertures shape a line of colored light passing through
the slit aperture, wherein there is a slit aperture corresponding to each
color of light produced by the light source.

11. The illumination source of claim 10, wherein the optical filter
further comprises multiple color filters, wherein there is one color
filter for each slit aperture, wherein each color filter blocks light
wavelengths outside of an intended range of light wavelengths for a line
of colored light passing through the slit aperture.

12. A method comprising:generating spots of colored light;focusing the
spots of colored light on a single diffuser;generating lines of colored
light from the spots of colored light;filtering the lines of colored
light; andscrolling the filtered lines of colored light.

13. The method of claim 12, wherein the generating lines of colored light
comprises passing the spots of colored light through a single reflective
or refractive diffuser having an array of lenticular elements or a random
or pseudorandom arrangement of structures.

14. The method of claim 12, wherein the filtering the lines of colored
light comprises:shape filtering the lines of colored light to produce
lines of desired shape; andcolor filtering the lines of colored light to
reduce light contamination.

15. The method of claim 14, wherein the shape filtering and the color
filtering are applied to each line in the lines of colored light
individually.

16. A method of manufacturing a display system, the method
comprising:installing a light source configured to generate coherent
light, wherein the light source installing comprisesinstalling a coherent
light source to produce colored light,installing a light shaping diffuser
in a light path of the coherent light source, the light shaping diffuser
to substantially simultaneously transform the colored light into lines of
colored light,installing a filter in the light path of the coherent light
source, the filter to shape the lines of colored light, andinstalling a
scrolling optics element in the light path of the coherent light source
after the filter, the scrolling optics element to scroll the lines of
colored light;installing a microdisplay in a light path of the display
system after the light source;installing a controller configured to
control the light source, the scrolling optics element, and the
microdisplay; andinstalling a display plane in the light path of the
display system after the microdisplay.

17. The method of claim 16, wherein the light shaping diffuser is
manufactured by machining or molding.

18. The method of claim 16, wherein the light shaping diffuser comprises
light diffusing structures and a body, wherein the light diffusing
structures and the body are manufactured in separate manufacturing steps,
and wherein the light diffusing structures are attached to the body using
an adhesive or a glue.

20. The method of claim 16, wherein the filter comprises an optically
opaque body having multiple slit apertures, and wherein the filter is
manufactured by machining the multiple slit apertures in the optically
opaque body.

[0002]The present invention relates generally to a system and method for
displaying images, and more particularly to a system and method for
uniform light generation in projection display systems.

BACKGROUND

[0003]In a microdisplay-based projection display system, light from a
light source may be modulated by the microdisplay as the light reflects
off the surface of the microdisplay or passes through the microdisplay.
Examples of commonly used microdisplays may include digital micromirror
devices (DMD), deformable micromirror devices, transmissive, reflective,
or transflective liquid crystal, liquid crystal on silicon, ferroelectric
liquid crystal on silicon, and so forth. In a digital micromirror device
(DMD)-based projection system, where large numbers of positional
micromirrors may change state (position) depending on an image being
displayed, light from the light source may be reflected onto or away from
a display plane.

[0004]For image quality reasons, it may be desirous to maximize the
brightness of the images being displayed. In general, the brighter the
images, the better the perceived image quality. Therefore, there have
been many techniques utilized to help improve image brightness. Some of
the techniques may include increasing the brightness of the light source,
using multiple light sources, and so forth.

[0005]In a laser illuminated, microdisplay-based projection display
system, it may be possible to maximize image brightness by increasing the
duty cycle of the laser(s) used to illuminate the microdisplay. Scanning
the light produced by the laser(s) so that more than one color of light
may simultaneously illuminate the microdisplay may be performed to
increase the duty cycle of the laser(s). That is, if only one color of
light may illuminate the entire microdisplay at a time, then all of the
other lasers must be turned off. However, if scanning permits the light
from a first laser and the light from a second laser to illuminate
different portions of the microdisplay, then the on-time of the first and
the second lasers may be increased, thereby increasing the duty cycle of
the lasers.

[0006]However, the light, produced by the laser(s), should be uniform or
relatively uniform to produce a uniformly illuminated image on the
display plane when scanned. If the light is not sufficiently uniform,
variations in illumination may be seen in the image. Furthermore, if
multiple colored lights are used, then the multiple colors of lights
should have substantially identical intensity profiles to prevent the
appearance of color bands in the image on the display plane.

SUMMARY OF THE INVENTION

[0007]These and other problems are generally solved or circumvented, and
technical advantages are generally achieved, by embodiments of a system
and method for uniform light generation in projection display systems.

[0008]In accordance with an embodiment, an illumination source is
provided. The illumination source includes a light source to produce
colored light, and a scrolling optics unit optically coupled to the light
source. The scrolling optics unit creates lines of colored light from the
colored light, and scrolls the lines of colored light along a direction
orthogonal to a light path of the illumination source. The scrolling
optics unit includes a single light shaping diffuser to transform the
colored light into the lines of colored light, an optical filter
positioned in the light path after the light shaping diffuser, and a
scrolling optics element positioned in the light path after the optical
filter. The optical filter shapes the lines of colored light, and the
scrolling optics element moves the lines of colored light in the
direction orthogonal to the light path.

[0009]In accordance with another embodiment, a method is provided. The
method includes generating spots of colored light, focusing the spots of
colored light on a single diffuser, and generating lines of colored light
from the spots of colored light. The method also includes filtering the
lines of colored light, and scrolling the filtered lines of colored
light.

[0010]In accordance with another embodiment, a method of manufacturing a
display system is provided. The method includes installing a light source
that generates coherent light, installing a microdisplay in a light path
of the display system after the light source, installing a controller
that controls the light source, a scrolling optics element, and a
microdisplay, and installing a display plane in the light path of the
display system after the microdisplay. The light source installing
includes installing a coherent light source to produce colored light,
installing a light shaping diffuser in a light path of the coherent light
source, installing a filter in the light path of the coherent light
source, and installing the scrolling optics element in the light path of
the coherent light source after the filter. The light shaping diffuser
substantially simultaneously transforms the colored light into lines of
colored light, the filter shapes the lines of colored light, and the
scrolling optics element scrolls the lines of colored light.

[0011]An advantage of an embodiment is that a single light diffuser may be
used for multiple colors of light. This may result in a high degree of
uniformity between the different colors of light. Therefore, images
created from the multiple colors of light may have uniform illumination
without the appearance of color bands.

[0012]A further advantage of an embodiment is that the use of a single
light diffuser in an illumination system may result in a simpler and less
expensive illumination system when compared to a similar illumination
system using multiple light diffusers.

[0013]The foregoing has outlined rather broadly the features and technical
advantages of the present invention in order that the detailed
description of the embodiments that follow may be better understood.
Additional features and advantages of the embodiments will be described
hereinafter which form the subject of the claims of the invention. It
should be appreciated by those skilled in the art that the conception and
specific embodiments disclosed may be readily utilized as a basis for
modifying or designing other structures or processes for carrying out the
same purposes of the present invention. It should also be realized by
those skilled in the art that such equivalent constructions do not depart
from the spirit and scope of the invention as set forth in the appended
claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]For a more complete understanding of the embodiments, and the
advantages thereof, reference is now made to the following descriptions
taken in conjunction with the accompanying drawings, in which:

[0015]FIG. 1a is a diagram of a portion of a microdisplay-based projection
display system;

[0016]FIG. 1b is a diagram of light output from a light source operating
in sequential color mode;

[0017]FIG. 2a is a diagram of a DMD-based projection display system;

[0018]FIG. 2b is a diagram of an illumination system;

[0019]FIG. 2c is a diagram of a line generator;

[0020]FIG. 2d is a diagram of a top view of a DMD illuminated by lines of
light;

[0027]FIG. 5 is a diagram of a sequence of events in the manufacture of a
projection display system; and

[0028]FIG. 6 is a diagram of a sequence of events in the generating of
lines of colored light.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0029]The making and using of the embodiments are discussed in detail
below. It should be appreciated, however, that the present invention
provides many applicable inventive concepts that can be embodied in a
wide variety of specific contexts. The specific embodiments discussed are
merely illustrative of specific ways to make and use the invention, and
do not limit the scope of the invention.

[0030]The embodiments will be described in a specific context, namely a
laser illuminated, microdisplay-based projection display system, wherein
the microdisplay is a DMD. The invention may also be applied, however, to
other laser illuminated, microdisplay-based projection display systems,
such as projection display systems utilizing deformable micromirror
devices, transmissive, reflective, or transflective liquid crystal
displays, liquid crystal on silicon displays, ferroelectric liquid
crystal on silicon displays, and so forth.

[0031]FIG. 1a illustrates a portion of a microdisplay-based projection
display system 100. The microdisplay-based projection display system 100
includes a light source 105 and a microdisplay 110. The light source 105
may be used to provide light that illuminates the microdisplay 110. The
light source 105 may produce light one color at a time. FIG. 1b
illustrates a time-space diagram of a sequence of colored light with N
unique colors. For example, the light source 105 may produce color number
1 (block 120), which may be followed by color number 2 (block 125), which
may be followed by the remaining N-2 colors, until the light source 105
may produce color number N (block 130). After producing color number N
(block 130), the light source 105 may repeat the color sequence and
produce color number 1 (block 120), etc.

[0032]Although shown in FIG. 1a as each laser having equal duty cycle, the
lasers of the light source may have different duty cycles. For example,
in a three laser light source, a first laser may have a 1/5 duty cycle
and the second laser and the third may have a duty cycle. The duty
cycle of each laser may depend on factors such as perceived color
brightness, desired color point, laser power, and so forth. In light
sources where certain colors may be produced by combining light from
several lasers, the duty cycle of each laser may also differ. For
example, in a RGBCYMW light source, there may be three separate lasers R,
G, and B, while the colors C, Y, and M may be produced by combining light
from two of the three lasers, and the color W may be produced by
combining light from all three lasers.

[0033]FIG. 2a illustrates an exemplary laser illuminated DMD-based
projection display system 200. The DMD-based projection display system
200 includes a DMD 205 that modulates light produced by a light source
210. The light source 210 may make use of multiple lasers to produce the
desired colors of light. For example, the light source 210 may include
three lasers, a red (R) laser, a green (G) laser, and a blue (B) laser.
By turning on individual lasers and/or multiple lasers, the light source
210 may produce multiple color combinations, such as a three-color RGB
color combination, a seven-color RGBCYMK color combination, and so forth.
Although the discussion focuses on solid-state lasers, other sources of
coherent light, including filtered non-coherent light, free-electron
lasers, and so forth, may be used in place of the solid-state lasers.
Therefore, the discussion should not be construed as being limited to the
present embodiments.

[0034]The DMD 205 is an example of a microdisplay or an array of light
modulators. Other examples of microdisplays may include transmissive or
reflective liquid crystal, liquid crystal on silicon, ferroelectric
liquid-crystal-on-silicon, deformable micromirrors, and so forth. In a
microdisplay, a number of light modulators may be arranged in a
rectangular, square, diamond shaped, and so forth, array. Each light
modulator in the microdisplay may operate in conjunction with the other
light modulators in the microdisplay to modulate the light produced by
the light source 210. The light modulated by the DMD 205 may be used to
create images on a display plane 215. The DMD-based projection display
system 200 also includes an optics system 220, which may be used to
collimate and/or focus the light produced by the light source 210 as well
as to reject stray light. The optics system 220 may also be used to
create lines of colored light from spots of colored light produced by the
light source 210. The DMD-based projection display system 200 may also
include a lens system 225, which may be used to manipulate (for example,
focus) the light reflecting off the DMD 205.

[0035]Also included in an optical path of the DMD-based projection display
system 200 may be a light scrolling unit 222. The light scrolling unit
222 may be used to scroll or scan light from the light source 210 onto
different portions of the DMD 205 and away from other portions of the DMD
205. This may allow for the simultaneous illumination of the DMD 205 by
light of different colors. For example, a red colored light may
illuminate a top third of the DMD 205, while a green colored light may
illuminate a middle third of the DMD 205, and a blue colored light may
illuminate a bottom third of the DMD 205. This may enable a higher duty
cycle for the lasers used in the light source 210, thereby increasing the
brightness of the images produced by the DMD-based projection display
system 200. Collectively, the light source 210, the optics system 220,
and the light scrolling unit 222 may be referred to as an illumination
system 223 of the DMD-based projection display system 200, with the
optics system 220 and the light scrolling unit 222 forming a scrolling
optics unit.

[0036]The DMD 205 may be coupled to a controller 230, which may be
responsible for loading image data into the DMD 205, controlling the
operation of the DMD 205, providing micromirror control commands to the
DMD 205, controlling the light produced by the light source 210, and so
forth. A memory 235, which may be coupled to the DMD 205 and the
controller 230, may be used to store the image data, as well as
configuration data, color correction data, and so forth.

[0037]FIG. 2b illustrates a detailed view of the illumination system 223.
The illumination system 223 includes the light source 210, the optics
system 220, and the light scrolling unit 222. The light source 210
includes multiple laser light sources, such as a red laser 250, a green
laser 251, and a blue laser 252. Each of the laser light sources may have
a first optical element(s) positioned at a light output of the laser
light source to provide light processing such as filtering, focusing, and
so forth. Additionally, the first optical element(s) may collimate the
light from the laser light sources. An optical fiber may be used to
couple the laser to the first optical element. For example, optical
element 255 may be at the output of the red laser 250, optical element
256 may be at the output of the green laser 251, and optical element 257
may be at the output of the blue laser 252. Although the discussion
focuses on the light source 210 having three primary color lasers, the
embodiments may be applicable to light sources having a different number
of lasers as well as different colors. Therefore, the discussion of the
light source 210 having three primary colors should not be construed as
being limiting to either the scope or the spirit of the embodiments.

[0038]The optics systems 220 includes multiple optical elements that may
be used to optically process light produced by the light source 210 into
a form that may be modulated by the DMD 205 to create images on the
display plane 215. The optics system 220 may include a second optics
element(s) 260 that may focus collimated light from the light source 210
onto a speckle reduction element 262. Furthermore, if the light source
210 does not produce collimated light, the second optics element(s) 260
may include a light collimator optical element.

[0039]When scattered by a rough surface, such as a display plane, a wall,
or so forth, the coherent light produced by a laser light source may
produce a modulating spatial noise having high contrast. The modulating
spatial noise, commonly referred to as speckle, may be highly
objectionable to viewers. Light fields from each of the individual
scatterers on the surface of the display plane, wall, or so on, may add
coherently and sum as phasors resulting in a randomly varying intensity
across the display plane, wall, or so on. The speckle reduction element
262, such as a spinning 0.5 degree diffuser, may help to reduce speckle.
Techniques in speckle reduction are considered to be well understood by
those of ordinary skill in the art of the embodiments and will not be
discussed further herein.

[0040]The optics system 220 also includes a line generator 264. The line
generator 264 may be used to convert spots of colored light as produced
by the light source 210 into lines of colored light. The line generator
264 may be implemented as a single light shaping diffuser. The light
shaping diffuser may shape light refractively or reflectively. The line
generator 264 may shape the far-field light distribution of a collimated
laser beam from a spot to a line. The line generator 264 may be located
in a pupil plane of the DMD-based projection display system 200 and may
displace spots of colored light in angle through a pupil so that the
light shaping diffuser may generate lines of colored light from the spots
of colored light. For example, if the spots of colored light are
displaced in an object plane, then the resulting lines of colored light
may be separated in an image plane, with a shape of the lines of colored
light being determined by the line generator 264.

[0041]FIG. 2c illustrates a view of the line generator 264. The line
generator 264 may be implemented as a single light shaping diffuser.
Laser light from the light source 210 may strike a surface of the line
generator 264 at different portions of the surface. As the laser light
from the light source 210 arrives at the line generator 264, it may have
the shape of a spot of light, such as spot 280, and it may have been
collimated by the first optical element(s), such as optical elements
255-257. As the laser light passes through the line generator 264, the
spot 280 may be reshaped into a line, such as line 282. As illustrated in
FIG. 2c, the line generator 264 converts three spots of light into three
lines of light. The use of three spots of light from the light source 210
is for illustrative purposes only, and the line generator 264 may be
capable of converting a number of spots of light into corresponding lines
of light. Therefore, the discussion of three spots of light should not be
construed as being limiting to either the scope or the spirit of the
embodiments.

[0042]When multiple collimated beams of laser light pass through generally
the same area of the line generator 264, implemented as a single light
shaping diffuser, optical variations may be significantly reduced from
those of a system using multiple light shaping diffusers. The use of the
single light shaping diffuser reshapes the multiple colored light spots
produced by the light source 210 into colored light lines, with each
colored light line having substantially the same intensity profile and
illumination distribution. This may lead to images being produced without
undesirable color stripes and so forth.

[0043]Turning back now to FIG. 2b, after the light from the light source
210 has been reshaped from spots of light into lines of light by the line
generator 264, the lines of light may receive further optical processing
by a third optical element(s) 266. The third optical element(s) 266 may
be used to focus, filter, and so forth, the lines of light from the line
generator 264.

[0044]The optics system 220 may also include an optical filter 268. The
optical filter 268 may be used to help prevent stray light from the line
generator 264 from passing through and unintentionally illuminating the
DMD 205 and consequently the display plane 215. The optical filter 268
may be implemented as an optically opaque plate with slit apertures, with
one slit aperture per line of light. For example, the optical filter 268
may have three slit apertures for light sources, such as the light source
210, that are capable of producing three lines of light.

[0045]Furthermore, the optical filter 268 may include color filters, such
as dichroic color filters, that may be used to help prevent stray light
from a first line of light from contaminating a second line of light. In
general, the color filters may be used to help ensure that light having
desired color characteristics (i.e., light having desired wavelengths)
may pass through the optical filter 268. In addition to dichroic color
filters, volume holographic optical elements may also be used as color
filters. Bragg planes, which generally are planes of alternating high and
low-index dielectric material within a volume hologram, may be designed
to reflect or transmit a light having a narrow band of wavelengths.
Furthermore, absorptive color filters may also be used. For example, a
slit aperture intended to shape a red colored line of light may include a
red colored filter that may permit only light having wavelengths in a
desired red portion of the light spectrum to pass. If, prior to passing
through the optical filter 268, the red colored line of light includes
light of other wavelengths, then the red colored filter in the optical
filter 268 may prevent the light of other wavelengths from passing and
pass only the red wavelengths of light.

[0046]After optical processing by the optical filter 268, the lines of
light may be scrolled over the surface of the DMD 205 by the light
scrolling unit 222. The light scrolling unit 222 includes a scrolling
optics element 270, such as a reflective or refractive rotating polygon
or a flower wheel. A reflective or refractive rotating polygon may be
described as a multi-faceted rotating body having lens elements and/or
mirrors arranged about its circumference, while a flower wheel may be
described as a rotating disk having a set of optics elements arranged
along a circumference around a center of the rotating disk. The scrolling
optics element 270 may be used to scroll the lines of light produced by
the line generator 264 over the surface of the DMD 205. The scrolling
optics element 270 may be rotated by a motor 272 coupled to the scrolling
optics element 270. The scrolling optics element 270 may be rotated about
an axis with the axis orthogonal to a light path of the lines of light in
the case of reflective or refractive rotating polygons or parallel to the
light path of the lines of light in the case of the flower wheel.

[0047]FIG. 2d illustrates a top view of the DMD 205. Shown in the surface
of the DMD 205 are several lines of differently colored light, for
example, a red colored light (shown as dashed light line 290) may
illuminate a top portion of the surface of the DMD 205, while a green
colored light (shown as dotted light line 292) may illuminate a middle
portion of the surface of the DMD 205, and a blue colored light (shown as
solid light line 294) may illuminate a bottom-middle portion of the
surface of the DMD 205. Furthermore, a bottom portion of the surface of
the DMD 205 is illuminated by a part of the dashed light line 290,
representing the red colored light. As the red colored light moves off
the bottom portion of the surface of the DMD 205, it reappears at the top
portion of the surface of the DMD 205. Alternatively, a color may
completely move off the bottom portion of the DMD 205 before reappearing
at the top portion of the DMD 205.

[0048]The lines of light as created by the illumination system 223
preferably occupy a portion of the surface of the DMD 205 that is less
than a reciprocal of the number of lines of light. For example, if there
are three lines of light illuminating the surface of the DMD 205, then
each line of light preferably has a thickness of less than one third of
the surface of the DMD 205. Therefore, there may be portions of the
surface of the DMD 205 that are unilluminated between the lines of light.
For example, a portion 296 of the surface of the DMD 205 is unilluminated
by light from the light source 210. The unilluminated portions of the
surface of the DMD 205 may allow for the loading of image data into the
light modulators of the DMD 205.

[0049]FIG. 3a illustrates a view of the light shaping diffuser 264. The
light shaping diffuser 264 may reshape spots of light into lines of light
by having a periodic array of lenticular structures, such as lenticular
structures 305 and 306, on a body 307 of the light shaping diffuser 264.
The lenticular structures 305 and 306 should have a pitch (shown as
highlight 310) that is substantially greater than a longest wavelength of
light expected to pass through the light shaping diffuser 264. The pitch
being substantially greater than the longest wavelength of light may
ensure that the light spreading is due primarily to refraction rather
than diffraction. This may help to minimize uniformity differences
between light of different wavelengths. Additionally, the lenticular
structures 305 and 306 may preferably be oriented so that they are
orthogonal to an intended orientation of the lines of light created by
the light shaping diffuser 264. For example, the vertical orientation of
the lenticular structures 305 and 306 may produce lines of light having a
horizontal orientation.

[0050]The lenticular structures, such as the lenticular structures 305 and
306, of the light shaping diffuser 264 may be arranged on a single
surface of the light shaping diffuser 264, wherein the single surface may
either be a surface wherein the spots of light enter the light shaping
diffuser 264 or a surface wherein the lines of light exit the light
shaping diffuser 264. Alternatively, they may be arranged on both the
light entering and exiting surfaces of the light shaping diffuser 264.

[0051]The light shaping diffuser 264 (the body 307 and/or the lenticular
structures) may be formed from a transparent or substantially transparent
material, such as glass, plastic, polymethylmethacrylate (PMMA),
polycarbonate, polyester, mylar, acrylic, polymethyl-pentene, and so
forth. The light shaping diffuser 264 may be created by machining.
Alternatively, the light shaping diffuser 264 may formed in a single
molding step or the lenticular structures may be molded separately and
then attached to each other and to the body 307 of the light shaping
diffuser 264 using an adhesive, glue, heat, sound waves, or so on.
Generally, care should be taken to ensure that significant light loss at
an interface between the lenticular structures 305 and 306 and the body
307 is prevented.

[0052]FIG. 3b illustrates a view of the light shaping diffuser 264. The
light shaping diffuser 264 may reshape spots of light into lines of light
by having a random or pseudorandom arrangement of structures, such as
structures 315 and 316, on the body of the light shaping diffuser 264.
The structures 315 and 316 should have a feature size (shown as highlight
320) that is substantially greater than a longest wavelength of light
expected to pass through the light shaping diffuser 264. Again, the
feature size being substantially greater than the longest wavelength of
light may ensure that the light spreading is due primarily to refraction
rather than diffraction. This may help to minimize uniformity differences
between light of different wavelengths. Furthermore, the structures 315
and 316 may preferably be oriented so that they are generally orthogonal
to an intended orientation of the lines of light created by the light
shaping diffuser 264. For example, the vertical orientation of the
structures 315 and 316 shown in FIG. 3b may produce lines of light having
a horizontal orientation.

[0053]The structures, such as the structures 315 and 316, of the light
shaping diffuser 264 may be arranged on a single surface of the light
shaping diffuser 264, wherein the single surface may either be a surface
wherein the spots of light enter the light shaping diffuser 264 or a
surface wherein the lines of light exit the light shaping diffuser 264.
Alternatively, they may be arranged on both the light entering and
exiting surfaces of the light shaping diffuser 264. The structures may be
created by using a relief mold containing positives or negatives of the
structures to form the light shaping diffuser 264, for example.

[0054]FIG. 3c illustrates a simplified view of the light shaping diffuser
264, wherein the light shaping diffuser 264 operates reflectively. The
diagram is simplified with structures, such as the lenticular structures
305 and the structures 315, omitted to maintain simplicity. The light
shaping diffuser 264 includes the body 307 and a reflective coating 330
applied to a surface of the body 307. The reflective coating 330 is shown
in FIG. 3c as being about as thick as the body 307. This is only for
illustrative purposes only, to simplify the illustration of the
reflective coating 330; typically, the reflective coating 330 is thinner
than the body 307.

[0055]Light, such as beams of collimated laser light, each of which may
exhibit the shape of a circular spot in the far field sufficiently far
from the laser source, may enter the light shaping diffuser 264 on a
surface of the body 307 opposite the reflective coating 330. After
passing through the body 307, the collimated laser light reflects off the
reflective coating 330 and once again passes through the body 307. The
collimated laser light then exits the light shaping diffuser 264 in the
form of lines of light.

[0056]FIGS. 3d and 3e illustrate photomicrographs of surfaces of light
shaping diffusers 264. The surface of the light shaping diffuser 264
shown in FIG. 3d is made up of structures having a random (or
pseudorandom) orientation while the surface for the light shaping
diffuser 264 shown in FIG. 3e is made up of structures having a generally
parallel or horizontal orientation.

[0057]FIG. 4a illustrates a view of the optical filter 268. The optical
filter 268 is shown having three slit apertures, such as slit aperture
285, formed in a body 286. Each slit aperture may be intended for use
with a particular line of light, for example, the slit aperture 285 may
be used to shape a line of red colored light. The slit aperture 285 is
shown as having a rectangular shape, but the shape of a slit aperture may
be dependent on factors such as a desired shape for the line of light,
wavelength of the light, and so forth.

[0058]The body 286 of the optical filter 268 may be formed from an
optically opaque material, such as a metallic material, an opaque glass
or plastic, a non-opaque glass or plastic with an opaque coating on at
least one surface, or so forth. The optical filter 268 may be formed by
machining or by molding techniques.

[0059]FIG. 4b illustrates a view of the optical filter 268. The optical
filter 268 is shown having three slit apertures, such as slit aperture
285, and color filters, such as color filter 287, positioned in front of
corresponding slit apertures, such as the slit aperture 285. Although
shown in FIG. 4b to be positioned in front of the slit apertures, the
color filters may be positioned in front of, behind, or inserted in the
slit apertures of the optical filter 268.

[0060]The color filters, such as the color filter 287, may be formed by
machining or molding the color filter from materials such as glass or
plastic having desired optical wavelength filtering characteristics.
Alternatively, the color filters may be created from materials not having
the desired optical wavelength filtering characteristics and the desired
optical wavelength filtering characteristics may be added by way of a
coating, film, implant, and so forth. The color filters may be machined
or molded in a separate step and then attached to the optical filter 268
using an adhesive, glue, heat, sound waves, or so on. Alternatively, the
color filters may be formed from the same material as the body of the
optical filter 268 and then a coating, film, implant, or so on, having
desired optical wavelength filtering characteristics may be applied to
the color filters.

[0061]FIG. 5 illustrates a sequence of events 500 in the manufacture of an
exemplary microdisplay-based projection display system. The manufacture
of the microdisplay-based projection display system may begin with
installing a light source, which may produce multiple lines of colored of
light (block 505). The installing of the light source may include the
installing of a line generator unit such as a light diffuser to convert
spots of light into lines of light (block 530). Also installed may an
optics unit (block 535). The optics unit may include an optical filter to
shape the lines of line as well as ensure that only desired colors of
light exit the light source that may be installed (block 540) along with
a light scrolling unit to scroll the lines of light over the surface of
the microdisplay (block 545).

[0062]The manufacture may continue with installing a spatial light
modulator such as a microdisplay, for example, a DMD, in the light path
of the multiple colors of light produced by the light source (block 510).
After installing the microdisplay, optical components such as a lens
system may be installed in between the light source and the microdisplay
(block 515). A controller for the microdisplay-based projection display
system may then be installed (block 520). With the controller installed,
the manufacture may continue with installing a display plane (block 525).
The order of the events in this sequence may be changed, the sequence may
be performed in a different order, or some of the steps may be performed
at the same time to meet particular manufacturing requirements of the
various embodiments of the DMD, for example.

[0063]FIG. 6 illustrates a sequence of events 600 in the generating of
scrolling lines of colored light. The generating of scrolling lines of
colored light may begin with generating of spots of colored light (block
605), such as from a light source having multiple laser light sources.
From the spots of colored light, the lines of colored light may be
generated (block 610).

[0064]The generating of the lines of colored light from the spots of
colored light may include focusing the spots of colored light onto a
surface of a single diffuser (block 615). The diffuser may be a light
shaping diffuser of sufficient size to permit the simultaneous focusing
of the spots of colored light. The light shaping diffuser may include an
array of lenticular elements or a random or pseudorandom arrangement of
structures that may be used to generate lines of colored light from the
spots of colored light (block 620). The lines of colored light may then
be filtered with an optical filter to provide a desired shape for the
lines of light (block 625). The optical filter may also include color
filters to help reduce or eliminate color contamination in the lines of
colored light. The filtered lines of colored light may then be scrolled
by a light scrolling unit (block 630).

[0065]Although the embodiments and their advantages have been described in
detail, it should be understood that various changes, substitutions and
alterations can be made herein without departing from the spirit and
scope of the invention as defined by the appended claims. Moreover, the
scope of the present application is not intended to be limited to the
particular embodiments of the process, machine, manufacture, composition
of matter, means, methods and steps described in the specification. As
one of ordinary skill in the art will readily appreciate from the
disclosure of the present invention, processes, machines, manufacture,
compositions of matter, means, methods, or steps, presently existing or
later to be developed, that perform substantially the same function or
achieve substantially the same result as the corresponding embodiments
described herein may be utilized according to the present invention.
Accordingly, the appended claims are intended to include within their
scope such processes, machines, manufacture, compositions of matter,
means, methods, or steps.